Valve tappet



Oct. 18, 1966 A. c. H. RAPPA 3,279,446

VALVE TAPPET Filed June 12, 1964 2 Sheets- Sheet 1 INVENTOR. ALFED C. R

Oct. 18, 1966 A. c. H. RAPPA 3,

VALVE TAPPE'I Filed June 12, 1964 2 Sheets-Sheet 2 INVENTOR. PLFReo Q.\ RAPPA United States Patent 3,279,446 VALVE TAPPET Alfred C. H. Rappa, Saginaw, Mich., assignor to Eaton Yale & Towne Inc., a corporation of Ohio Filed June 12, 1964, Ser. No. 374,775 8 Claims. (Cl. 123-90) The present invention relates, generally, to valve tappets for use with internal combustion engines.

More particularly, this invention pertains to a weight reduction tappet of cast metal or an alloy which can be accurately and uniformly ground in a centerless grinding operation.

The centerless grinding operation entails placing the tappet to be ground on a holding member positioned between a grinding wheel and a tappet driving wheel or between a pair of grinding wheels, one of which drives the tappet. With the normal type of weight reduction tappet, i.e., one having upper and lower end lands. with longitudinally or vertically extending, radially spaced webs disposed therebetween, it is difficult to obtain a constant cross-sectional circular shape of the tappet body in a centerless grinding operation. This is because of the variations in grinding pressure between the tappet and the grinding wheel or wheels as it rotates therebetween. These variations in grinding pressure are caused by variations in the surface of the tappet in contact with each grinding wheel during the grinding operation. As the tappet is rotating, the outer surface thereof in contact with the grinding wheel varies from the full length of the tappet, as the upper and lower end lands and one of the longitudinal webs engage the grinding wheel, to a very small area, as only the end lands engage the grinding wheel when one of the recessed portions of the tappet body between the webs is adjacent the wheel.

In the latter situation, when only the end lands engage the grinding wheel, there is a greater grinding pressure on the peripheral portions of each of the end lands adjacent the recesses in the tappet body than there is on the peripheral portions of the end lands adjacent the longitudinal webs when the latter are in contact with the grinding wheel. Thus, more metal is removed from the peripheral portions of the end lands adjacent the tappet body recesses, and this results in undesirable variations in the diameter of the finished tappet at and adjacent to the end lands thereof.

The present invention contemplates a unique valve tappet of the weight reduction type which may be substantially uniformly ground in a centerless grinding operation. This is accomplished by providing the valve tappet body with transverse, helical or spiral webs instead of transverse and straight, longitudinally extending webs between the end lands of the body. The helical webs are substantially constantly in contact with the grinding wheel during the centerless grinding operation and thus the grinding pressure on the webs and end lands of the tappet body remains relatively constant to insure that the finished tappet will be substantially constant in diameter throughout the length thereof.

It is a primary object of the present invention, therefore, to provide a valve tappet of the weight reduction type which can be substantially uniformly ground in a centerless grinding operation.

It is another primary object of this invention to provide a valve tappet of the weight reduction type having a construction that presents a substantially constant grinding area to the grinding wheel or wheels of centerless grinding apparatus.

A further primary object of the present invention is the provision of a valve tappet of cast metal or an alloy which comprises end lands and spaced webs extending therebetween, the webs being so constructed and shaped as to provide a substantially constant grinding surface on the tappet as it is rotating in engagement with a grinding wheel of a centerless grinder.

Still another primary object of this invention is to provide a valve tappet of the weight reduction type which comprises end lands and spaced helical webs extending therebetween, the helical webs providing a substantially constant grinding surface on the tappet when it is ground in centerless grinding apparatus.

Other objects and important features of the invention will be apparent from a study of the specification following taken with the drawing, which together show, illustrate, describe and disclose a preferred embodiment or modification of the invention and what is now considered to be the best mode of practicing the principles there. Other embodiments or modifications may be suggested to those having the benefit of the teachings herein, and such other embodiments or modifications are intended to be reserved especially as they fall within the scope and spirit of the subjoined claims.

In the drawings:

FIGURE 1 is an elevational view, partly in section and with parts broken away, showing a valve tappet mounted in an internal combustion engine block;

FIGURE 2 is an enlarged, partial elevational view, partly in section of the valve tappet and push rod shown in FIGURE 1;

FIGURE 3 is a side elevational view of centerless grinding apparatus for the valve tappet;

FIGURE 4 is a front elevational view of a valve tappet constructed according to the principles of the instant invention;

FIGURE 5 is a side elevational view of the tappet shown in FIGURE 4;

FIGURE 6 is a sectional view taken substantially along line 6-6 of FIGURE 5;

FIGURE 7 is a sectional view taken substantially along line 7-7 of FIGURE 5;

FIGURE 8 is a front elevational view of a modified valve tappet;

FIGURE 9 is a side elevational view of the modified tappet shown in FIGURE 8;

FIGURE 10 is a sectional view along line 10-10 of FIGURE 9; and

FIGURE 11 is a sectional view taken substantially along line 11-11 of FIGURE 9.

Referring now to the drawings, there is illustrated in FIGURE 1 the block 20 of an internal combustion engine. A generally cylindrical tappet 22 of cast metal or an alloy is slidably mounted in a passageway 24 in the block 20 and has the lower end or land 26 thereof resting on a cam 28 mounted on a rotatable cam shaft 30. The upper end or land 32 of the tappet 22 is provided with a generally cup-shaped seat 34 (see FIGURES 1 and 2) in which the spherical end portion 36 of a valve actuating or push rod 38 is disposed. The tappet 22, therefore, serves to reciprocate the valve-actuating rod 38 in accordance with the shape of the cam 28.

As shown in FIGURE 3, such valve tappets 22 are normally ground to final shape and finish by a centerless grinding apparatus 40 comprising one or more grinding wheels 42 and 44 of any suitable construction which are rotatably mounted on a supporting frame 46, one of the wheels being rotatably driven by any suitable means (not shown). The tappet 22 is rotatably mounted between the grinding wheels 42, 44 on a support member 48 and has the outer surface thereof in engagement with the grinding wheels.

Referring now to FIGURES 4 through 7, the weight reduction tappet 22 of the instant invention comprises a taken substantially longitudinally or vertically extending cross web 50 disposed between the end lands 26 and 32 thereof. On each side of the cross Web 50 there are disposed or formed a pair of transverse and substantially parallel, helical or spiral webs 52, 54, the upper helical webs 52 extending between the upper end land 32 and the cross web 50, and the lower helical webs 54 extending between the cross web 59 and the lower end land 26. Preferably, the helical webs 52 and 54 are so disposed as to overlap throughout longitudinal and transverse planes of the tappet 22 (see FIGURES 4 and 5), for a reason to be described here inafter.

Since the webs 52 and 54 of the tappet 22 are helical and since they overlap throughout longitudinal and transverse planes of the tappet, the outer surface of the tappet 22 in engagement with the grinding wheels 42 and 44 of FIGURE 3 varies only slightly and thus remains relatively constant as the tappet rotates during the centerless grinding operation, with the result that there is a relaively constant grinding pressure on the tappet 22 and the finished tappet has a substantially uniform diameter throughout the length thereof. While the angle of helix of the helical webs 52, 54 is not critical, it is desirable that it be varied according to the diameter of the tappet 22 so that the variation in the amount of the peripheral surface of the tappet as it rotates in engagement with the grinding Wheels 42 and 44 is kept at a minimum.

Referring now to FIGURES 8 through 11, there is illustrated therein a modified tappet 122 which is substantially similar in construction to the tappet 22 of FIG- URES 4 through 7. The modified tappet 122 comprises end lands 126, 132 and a cross web 150 extending longitudinally therebetween. On each side of the cross web 150 there are formed a pair of substantially parallel, helical webs 152, 154, the upper helical webs 152 extending between the upper end land 132 and the cross web 150,( and the lower helical webs 154 extending between the cross web 150 and the lower end land 126. A short helical web 156 extends substantially transversely between the upper and lower helical webs 152 and 154, respectively, on either side of the cross web 150 (see FIGURES 8 and 9). The short transverse webs 156 serve to reinforce and strengthen the tappet body and to increase the column bending strength thereof in a plane which is approximately perpendicular to the cross web 150.

It is noted that it would be within the spirit and scope of the instant invention to provide a tappet having end lands and one or more spiral or helical webs extending therebetween, without providing a longitudinal cross web between the end lands. It is advantageous, however, to provide the cross web between the end lands, since it greatly facilitates the casting of a tappet having helical webs.

While the invention has been shown, illustrated, described and disclosed in terms of an embodiment or modification which it has assumed in practice, the scope of the invention should not be deemed to be limited by the precise embodiment or modification herein shown, illus trated, described or disclosed, such other embodiments or modifications intended to be reserved especially as they fall within the scope of the claims here appended.

What is claimed is: i

1. A generally cylindrical valve tappet comprising:

a first land at one end thereof having a cup-shaped recess therein for receiving one end of a valve actuating member,

a second generally fiat land at the other end thereof,

a cross web having a width approximately equal to the diameter of said first and second lands and extending longitudinally therebetween and formed integral therewith,

a first helical web extending between and formed integral with said first land and said cross web on each side of said cross web, and

a second helical web extending between and formed integral with said second land and said cross web on each side of said cross web, said second helical web being substantially parallel to said first helical web.

2. The valve tappet as recited in claim 1 wherein said first and second helical webs are so disposed as to overlap throughout longitudinal and transverse planes of the tappet.

3. The valve tappet as recited in claim 2 wherein a third helical web extends transversely between and is formed integral said first and second helical webs on each side of said cross web.

4. A generally cylindrical valve tappet, comprising:

a first land at one end thereof,

a second land at the other end thereof,

a cross web formed integral with and extending longitudinally between said first and second lands,

a first helical web extending between and formed integral with said first land and said cross web on each side of said cross Web, and

a second helical web extending between and formed integral with said second land and said cross web on each side of said cross web, said second helical Web being substantially parallel to said first helical web.

5. The valve tappet as recited in claim 4 wherein a third helical web extends between and is formed integral with said first and second helical webs on each side of said cross web.

6. A generally cylindrical tappet, comprising:

a first land at one end thereof,

a second land at the other end thereof, and

a pair of transverse, helical webs disposed in parallel relation between said first and second lands and formed integral therewith.

7. The tappet as recited in claim 6 wherein a helical web extends between and is formed integral with said pair of parallel helical webs.

8. A generally cylindrical valve tappet comprising:

a first land at one end having a cup shaped recess thereon for receiving one end of the valve actuating member,

a second land at the other end thereof, and

a transverse, helical web disposed between said first and said second lands and integral therewith.

References Cited by the Examiner UNITED STATES PATENTS 1,998,612 4/1935 Ford 12390 2,091,674 8/1937 Dostal l2390 2,324,006 7/ 1943 Lenz et al. l23-90 OTHER REFERENCES Publication: Lincoln-Mercury Service Bulletin, 1964 series, bulletin Number 24, February 21, 1964, page 2 (Ford Motor Company).

MARK NEWMAN, Primary Examiner.

A. L. SMITH, Assistant Examiner. 

8. A GENERALLY CYLINDER VALVE TAPPET COMPRISING: A FIRST LAND AT ONE END HAVING A CUP SHAPED RECESS THEREON FOR RECEIVING ONE END OF THE VALVE ACTUATING MEMBER, A SECOND LAND AT THE OTHER END THEREOF, AND A TRANSVERSE, HELICAL WEB DISPOSED BETWEEN SAID FIRST AND SAID SECOND LANDS AND INTEGRAL THEREWITH. 